Optical wavelength communication systems are highly desirable for use in many different applications. For example, such systems can be used to replace radio frequency systems, such as those used in fast food restaurants, since the optical wavelength systems do not require special government licenses and are more tolerant to noise interference.
For example, a short range, optical wavelength carrier communication system is disclosed in co-pending patent application Ser. No. 07/176,939, filed Apr. 4, 1988, and assigned to the same assignee as the subject application. In the co-pending application, the optical wavelength communication system enables full duplex communication between two or more transceivers. In this regard, both transceivers can communicate simultaneously with one another over a single optical wavelength carrier signal. A single optical wavelength carrier is used, and the carrier is shared on a time division multiplex basis to avoid the problems of sensitivity, should an outgoing signal interfere with an incoming signal. While such a wavelength carrier system may be highly useful for many applications, it would be highly desirable to have a wavelength communication system, which did not employ a time division multiplex arrangement. In this regard, it would be highly desirable to have a full duplex optical wavelength carrier communication system, which would not require complex time division multiplex synchronization circuits.
Therefore, it would be highly desirable to have a full duplex, optical wavelength carrier system, which operates either on a single or multiple wavelength carrier, without the need for time division multiplex synchronizing circuits. Such a system should be highly efficient and as sensitive as the time division multiplex system. In this regard, such a system should be arranged to prevent the outgoing signal from interfering with the incoming signal, thereby resulting in unwanted and undesirable insensitivity. Also, such a system should be relatively inexpensive to manufacture.